Mastitis is a common disease, principally caused by known organisms entering the mammary glands through the teat canal. These microbes include common bacteria which may be transmitted in numerous ways, including direct contact with the teats, as well as airborne transmission. Under the circumstances, mastitis occurs with high frequency in environments where the control of such bacterial population is not easily accomplished.
Mastitis is a particularly difficult problem in connection with dairy herds, since the teats of the cows are frequently manipulated for milking purposes, and in between milkings, the cows remain in barns or pasturage, where mastitis causing organisms can easily survive and proliferate. Further, an infected cow can contaminate conventional milking apparatus, stalls, cleaning materials and the like so that mastitis can easily spread through a dairy herd. Mastitis renders the cow unsuitable for commercial milking and, accordingly, a significant incidence of mastitis in a dairy herd can produce a crippling economic effect of the dairy farmer.
Therefore, it is a conventional practice in the dairy industry to protect dairy cows by applying an antimicrobial composition to the teats of the cows. While these compositions are broadly applicable to the teats of all mammals, since the major economic impact of mastitis is in connection with dairy cows, the following description of the invention will be in connection with and will reference the teats of cows, for the sake of conciseness, although it is to be understood that this term is to be construed in the specification and claims as embracing the teats of all mammals.
The providing of an effective and yet safe teat dip has presented considerable problems to the art. Since the teat dip is normally applied to the dairy cow after each milking, i.e. twice daily, it will be appreciated that many microbicides and compositions thereof are too harsh and irritating for repeated use on sensitive teat tissues. Further, the application of the teat dip to the teat allows ample opportunity for the microbicide to contaminate the milk. Thus, it is imperative that the microbicide of the teat dip be "water soluble or dispersible." Thus, the microbicide is easily washed from the teats to prevent contamination of the milk.
In the foregoing regard, U.S. Pat. No. 3,928,556 extensively discusses the irritating sting of polymer containing and bactericide containing liquid wound dressings, which can be used as a wound dressing to protect cows having mastitis on the teats, and suggests solvent systems with major amounts, i.e. at least 50% of non-stinging tert-butyl alcohol, along with minor amounts of stinging alcohols, e.g. lower alkanols and non-stinging hydrocarbon and fluorocarbon solvents. While these wound dressings are non-irritating (stinging is this case), they are not water-soluble and cannot be used as a routine teat dip.
Further, since the cow is most vulnerable to mastitis invasion during milking and immediately thereafter, teat dipping is most effective when performed immediately after milking. This provides protection from the environmental infection sources in the barn and pasture areas. Accordingly, it is highly desirable to provide a fast acting teat dip, since extended times for effectively using the dip will undesirably slow down the overall milking procedure or provide less than required mastitis protection. Thus, a desirable teat dip must be capable of providing an adequate kill of bacteria on the teat in a reasonably short time, e.g. ten minutes or less, since times beyond this period greatly limit the effectiveness of the teat dip.
In view of these exacting requirements, the art has produced only a few economical and effective teat dips. While many microbicides are known which can produce an adequate kill of the microbes in the required time, and even provide some residual effects, the resulting irritation of the teats and the lack of water-solubility or dispersibility reduces the possible candidates for this application most substantially. The teat dip most widely used contains iodine, since the iodine composition is water-soluble and fast acting, but iodine suffers from decided disadvantages. It is substantially irritating to the teats of cows, care must be taken to minimize the contamination of the milk with the toxic iodine, and iodine is a strong oxidizing agent and reacts quickly with most material it contacts. This latter property substantially reduces the residual microbicidal effect. This property also tends to substantially reduce any activity of other microbicides compounded with the teat dip.
U.S. Pat. No. 2,739,922 issued to Shelanski discloses a combination of iodine and polyvinylpyrrilodone and related film-forming polymers. This combination lowers both the acute toxicity and the chronic toxicity of the iodine and reduces the irritation and sensitization effects of iodine. While iodine staining is also mitigated, the combination does not totally obviate the same, and continued topical use will cause permanent staining of the skin. However, iodine and/or iodine-polyvinylpyrrilodone combinations still suffer from the disadvantages of toxicity and the reactivity of the iodine, even in the polyvinylpyrrilodone.
Accordingly, it would be of substantial advantage in the art to provide a teat dip which has a rapid kill of mastitis causing bacteria, can be repeatedly applied, without irritation to the teats, is not toxic, is water-soluble or dispersible, and will not stain or otherwise harm the teats. These properties would provide the advantages of the iodine-type teat dip, but without the disadvantages thereof.